Is it Worth Repairing My Old Boiler or Replacing It?

If your boiler is getting on and has started to play up, it's natural to wonder whether to keep paying for repairs or put the money towards a new one. For many boilers, a repair is still the sensible choice. But when a boiler is old, breaking down more often and needs an expensive part, replacing it is usually better value and more reliable over the next few winters.

This post explains how to weigh it up: the boiler's age, its repair history, parts, safety and running costs. You can check a few things yourself, such as its age and how often it has failed, but never take the casing off or try to repair a gas boiler yourself. That's a job for a Gas Safe registered engineer.

How long boilers usually last

Most modern gas boilers last around 10 to 15 years if they're serviced every year. Some go on much longer, and some fail sooner, especially if the heating system is full of sludge (a dark build-up of rust and dirt in the pipes and radiators) or the boiler has missed services.

Age on its own isn't a reason to replace a boiler that's working well. But once a boiler is past 10 years old, each repair is worth weighing against what it's likely to need next.

To find your boiler's age, look for the installation paperwork, the date on the last service record, or the model name on the front panel, which you can look up online.

When a repair makes sense

A repair is usually the right call when:

• the boiler is under about 10 years old

• it's had no other faults in the last year or two

• the fault is a single, common part, such as a pump, fan, valve or sensor

• the part is easy to get for your model

• the boiler has been serviced regularly and the engineer says it's otherwise in good condition

In these cases, fixing it is likely to give you several more years of reliable heating. Our boiler repair service starts by finding the cause, so you know exactly what's wrong before you decide.

When replacing is the better choice

It's usually time to think about a new boiler when:

• it's breaking down more than once a year

• the repair needed is a major part, such as the heat exchanger (the part that passes heat from the burning gas into your heating water), and the cost is a large share of a new boiler

• parts for your model are no longer made, or are hard to find

• your gas bills are creeping up even though you use the heating the same way

• it's an old back boiler (one fitted behind a gas fire in the fireplace) or a non-condensing boiler

A common rule of thumb is that if a repair would cost around half the price of a new boiler, and the boiler is over 10 years old, replacement is often the better long-term choice. It's a guide, not a rule, so ask your engineer to talk you through both options.

Why older boilers cost more to run

Since 2005, almost all new gas boilers fitted in England and Wales have had to be condensing boilers. A condensing boiler captures heat from its exhaust gases that older boilers send straight out of the flue (the pipe that carries fumes outside), so less gas is wasted.

If your boiler was fitted before then, it may well be non-condensing. A modern condensing boiler, set up properly with good controls, uses noticeably less gas to heat the same home. That saving won't pay for a new boiler overnight, but it does count over the 10 to 15 years it should last. A new boiler is also a good time to add better controls, which our post on adding smart controls during a boiler install covers.

When safety decides for you

Sometimes the choice is made for you. If an engineer finds a gas boiler unsafe, for example because it's producing too much carbon monoxide or the flue is damaged, they'll explain the problem and, with your permission, turn it off until it's put right. If the fix isn't possible or isn't worth it on an old boiler, replacement is the only safe option.

Between visits, a working carbon monoxide alarm near the boiler is essential. Call an engineer straight away if you notice a lazy yellow or orange flame instead of a crisp blue one, black marks or soot around the boiler, or a pilot light that keeps going out.

If you smell gas, open doors and windows, don't use light switches or anything that could cause a spark, turn the gas off at the meter if you can safely reach it, leave the property and call the National Gas Emergency Service on 0800 111 999.

Why it's worth deciding before winter

Most boilers that are struggling give up when they're working hardest, on the first really cold days. Deciding now means you can compare options calmly instead of in a rush with no heating or hot water.

An annual service is a good moment to ask the question. One of our customers explained that their mum's "very old back boiler would not have got through another winter following our yearly service", so the old boiler was removed and a new one was fitted in a new place, the airing cupboard. Spotting it at a service meant the work could be planned rather than done in an emergency.

What happens if you decide to replace it

If replacement is the right choice, an engineer visits first to look at your home, your hot water needs and where the boiler could go. The new boiler doesn't always have to go where the old one was, which is useful when an old back boiler is being taken out.

Our post on the step-by-step process of a boiler installation explains what happens on the day, from removing the old boiler to testing the new one and handing over the paperwork.

Getting an honest answer

Whittaker Plumbing & Heating is Gas Safe registered and accredited by Worcester Bosch, Vaillant and Glow-worm. We look at each boiler on its merits and explain the repair and replacement options, so you can decide what's right for your home and budget. If your boiler is older and you'd like it checked before winter, book a visit through our boiler installation page and we'll talk you through the options.